Fixed CORE-4237 - FB3 vs FB2.5. Different metadata for UDF return argument.

The is a case showing a difference between 2.5 and 3.0 in the first comment. The second comment does not show difference between versions.

git-svn-id: svn+ssh://svn.code.sf.net/p/firebird/code/firebird/trunk@58688 65644016-39b1-43b1-bf79-96bc8fe82c15